I have maybe a random take but I think I would have liked it better if her life with the prince was her first one all along, and she just chose differently with Escalante, instead of him being "the first and right one all along", but maybe that's also because I never liked the trope of lovers that had secretly already met when younger/as children and made a promise or something along those lines to signal fate. It always felt a lot more artificial to me than watching people stumbling through their choices, a lot less about characters' agencies, like everyone is some sort of passive recipient of their destiny. Though I do think it's going to be a lot more nuanced than that as well and this story plays a lot with "destiny" as a concept as well.
I feel like the meaning of these past memories are that they were both much younger and immature in their first lives as lovers, as well as people who symbolized so much power, and hurt each other, but now they are able to communicate properly and learn from their previous mistakes. That would be super interesting also, but we'll see!